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The following pages explain and illustrate a very reliable, simple, and effective method of prototyping (creating) electronic circuitry whereas conductor material that interconnects circuit board terminal pads is raised so that it does not adhere to epoxy that affixes the terminal pads to the circuit board. The conductive interconnects (circuit traces) between the terminal pads are selectively cut and removed so that the terminal pad interconnects that are left between the terminal pads form the conductive traces for an electrical circuit. This circuit construction method is also very good for producing finalized permanent circuitry after the prototyping is done (i.e., if the circuit prototype works properly then that same board is ready to be put in the electronic equipment as is).
Typically circuit boards have a 0.002xe2x80x3 thick copper plate that is affixed to the board surface with epoxy. These printed circuit boards are then coated with an etchant resist ink where the circuit traces are desired. The copper that is not covered by the etchant resist ink is then removed by an etchant solution such as ferric chloride. The resist ink is then removed with a solvent such as isopropyl alcohol. The copper that remains on the board forms the circuit traces. It usually takes about twenty minutes to etch a 0.002xe2x80x3 copper board using ferric chloride once the etchant resist has been applied in the proper pattern. Photo plotting, applying photo resist, using ferric chloride etchant solution and then drilling holes in the circuit board that have the proper standardized electronic component hole spacing, etc., is a time consuming and labor intensive task. However, making reliable permanent circuits using these E-Z CirCut boards with standardized hole spacing is incredibly easy.
Typical perforated boards with standardized hole spacing, with or without a variety of non-removable circuit interconnects are readily available from electronics suppliers such as your local Radio Shack, etc.
Previously, there have been three main methods of prototyping:
1. Jumper wire breadboards with press fit internal sockets.
2. xe2x80x98Wire wrapxe2x80x99 whereas circuits are created by using incredibly thin wire wrapped around extended metal posts.
3. Point-to-point wiring where wiring is simply soldered haphazardly from terminal pad to terminal pad.
In all kindness, all of these previous methods are lousy. Jumper wire breadboards with press fit internal sockets last only a short time before bad connections (everywhere) change their characteristics (especially with analog circuitry). They can""t be used with low noise circuitry at all. Bumping the board will cause it to be different than before. Looking at the board will also cause it to be different than before (especially with analog circuitry), etc. Methods 2and3 are almost equally lousy with wiring and, in the case of wire wrapping, bad connections everywhere. It is almost impossible to keep track of the circuitry during construction or to trace it later.
By punching selected standardized spaced holes in a plastic plate and then placing it over alignment posts that fit through a CirCut board a permanent marker can be placed through each hole until the circuit traces (terminal pad interconnects) that are not to be cut are all marked. As such, a large number of identical boards can be marked and then cut quickly and easily.
The advantages of selectively cutting raised removable interconnects between the circuit board terminal pads, other than those already mentioned, is that the boards circuit traces (terminal pad interconnects) can be much thicker. This is due to the fact that in order to be able to reliably etch a printed circuit board the metal must be thin (typically 0.002xe2x80x3). E-Z CirCut boards, on the other hand, do not have this requirement. Therefore, this new board design is better for many high-speed CMOS circuits, for instance. This is due to lower IR (IR is current multiplied by resistance which equals voltage) voltage drops in the circuit due to larger circuit traces (uncut interconnects between the terminal pads), which lowers the circuit resistance. Therefore, voltage spikes caused by a large number of capacitive CMOS gates changing simultaneously are reduced, etc. These CirCut boards are also much better for power circuitry in which, instead of large point to point wiring, the circuit traces for some of these new CirCut boards can, for instance, approximate a xe2x85x9xe2x80x3 inch diameter wire and can be doubled by using both sides of the board. In short, there are many reasons why these CirCut boards, in one form or another, are definitely in demand.
It usually takes about twenty minutes to etch a 0.002xe2x80x3 copper board using a ferric chloride etching solution, therefore, this E-Z CirCut board design can be very competitive for mass production runs. For instance, it is as easy to mow (cut or trim) a board, as it is to solder it. Besides, photo resist, photo plotting, ferric chloride, etc., must cost something. Also, these boards are digital in nature, not analog like most PC boards. This means that the location of each terminal pad interconnect (circuit trace) can easily be specified digitally since they are all part of a clearly defined grid pattern. For instance, mark interconnects A1to3, 3AtoD, D3to6.
An easy and reliable method for prototyping circuitry and creating solid circuit boards that can be used, as is, in production equipment. These CirCut boards can be double sided and can be produced without xe2x80x9cthrough holesxe2x80x9d for use with SMT (surface mount devices). For power circuitry they are ideal since their circuit traces can be much thicker than those of regular circuit boards. The position of each circuit trace (terminal pad interconnect) can be specified according to its grid location. Standard chips fit up above the circuit board (FIG. 11) and the terminal pad interconnects. Therefore, typically, two circuit traces can run underneath each chip (such as a 555 timer chip) between the chips legs. All the standard electronic components are completely compatible with the E-Z CirCut board design. The boards can be single or double sided (more circuit interconnects).
The key to this concept is the raised conductor interconnects between the terminal pads. These stay up off the board away from the epoxy that is used to affix the metal terminal pads of the grid to the circuit board therefore making the terminal pad interconnects (circuit traces) easy to selectively cut and remove.